linux-kernel - Re: [PATCH v3 3/3] mtd: spinand: add SPI-NAND MTD resume handler

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Date:   Fri, 28 May 2021 17:35:10 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     <patrice.chotard@...s.st.com>
CC:     Mark Brown <broonie@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        <linux-mtd@...ts.infradead.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <christophe.kerello@...s.st.com>
Subject: Re: [PATCH v3 3/3] mtd: spinand: add SPI-NAND MTD resume handler

On 27/05/21 06:12PM, patrice.chotard@...s.st.com wrote:
> From: Patrice Chotard <patrice.chotard@...s.st.com>
> 
> After power up, all SPI NAND's blocks are locked. Only read operations
> are allowed, write and erase operations are forbidden.
> The SPI NAND framework unlocks all the blocks during its initialization.
> 
> During a standby low power, the memory is powered down, losing its
> configuration.
> During the resume, the QSPI driver state is restored but the SPI NAND
> framework does not reconfigured the memory.
> 
> This patch adds SPI-NAND MTD PM handlers for resume ops.
> SPI NAND resume op re-initializes SPI NAND flash to its probed state.
> 
> Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>
> Signed-off-by: Patrice Chotard <patrice.chotard@...s.st.com>
> ---
> Changes in v3:
>   - Add spinand_read_cfg() call to repopulate cache
> 
> Changes in v2:
>   - Add helper spinand_block_unlock().
>   - Add spinand_ecc_enable() call.
>   - Remove some dev_err().
>   - Fix commit's title and message.
> 
>  drivers/mtd/nand/spi/core.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 1f699ad84f1b..e3fcbcf381c3 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1099,6 +1099,38 @@ static int spinand_block_unlock(struct spinand_device *spinand)
>  	return ret;
>  }
>  
> +static void spinand_mtd_resume(struct mtd_info *mtd)
> +{
> +	struct spinand_device *spinand = mtd_to_spinand(mtd);
> +	int ret;
> +
> +	ret = spinand_reset_op(spinand);
> +	if (ret)
> +		return;
> +
> +	ret = spinand_read_cfg(spinand);
> +	if (ret)
> +		return;
> +
> +	ret = spinand_init_quad_enable(spinand);
> +	if (ret)
> +		return;
> +
> +	ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
> +	if (ret)
> +		return;
> +
> +	ret = spinand_manufacturer_init(spinand);
> +	if (ret)
> +		return;
> +
> +	ret = spinand_block_unlock(spinand);
> +	if (ret)
> +		return;
> +
> +	spinand_ecc_enable(spinand, false);
> +}
> +

I don't think you quite get what me and Miquel are suggesting.

The helper should call all these functions like read_cfg() 
quad_enable(), etc. So it should look something like:

int spinand_init_flash()
{
	ret = spinand_read_cfg(spinand);
	if (ret)
		return;

	ret = spinand_init_quad_enable(spinand);
	if (ret)
		return;

	ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
	if (ret)
		return;

	ret = spinand_manufacturer_init(spinand);
	if (ret)
		return;

	ret = spinand_block_unlock(spinand);
	if (ret)
		return;

	spinand_ecc_enable(spinand, false);
}

Then spinand_mtd_resume should look something like:

int spinand_mtd_resume()
{
	ret = spinand_reset_op(spinand);
	if (ret)
		return;

	return spinand_init_flash();
}

And spinand_init() should look something like:

int spinand_init()
{
	...
	spinand->oobbuf = ...

	spinand_init_flash();

	spinand_create_dirmaps();

	...
}


>  static int spinand_init(struct spinand_device *spinand)
>  {
>  	struct device *dev = &spinand->spimem->spi->dev;
> @@ -1186,6 +1218,7 @@ static int spinand_init(struct spinand_device *spinand)
>  	mtd->_block_isreserved = spinand_mtd_block_isreserved;
>  	mtd->_erase = spinand_mtd_erase;
>  	mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
> +	mtd->_resume = spinand_mtd_resume;
>  
>  	if (nand->ecc.engine) {
>  		ret = mtd_ooblayout_count_freebytes(mtd);
> -- 
> 2.17.1

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.